Organic Chemistry

All Hydrocarbons Molecular compounds Apart of a Homologous series - same General formula and functional group (site where reactions occur) Saturated hydrocarbons - all atoms linked by single covalent bonds Molecular - weak intermolecular forces MPt + BPt - increase with length of carbon chain. As molar mass increases, more electrons attracted to the neighbouring nuclei of molecules, so Van der Waals forces are stronger and there is more energy required to break them Solubility - all insoluble. Non-polar because C-H are non-polar Soluble in cyclohexane

Alkanes

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Rubrica: : General Formula CnH2n+2 (subscripts)

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Structural Isomers of Alkanes

Combustion and Substitution of Alkanes

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Rubrica: : Substitution - needs UV light - Bromine solution decolourises

Rubrica: : Complete combustion

Alkenes - CnH2n - ene

Unsaturated hydrocarbons - contain double C bonds CnH2n Addition reaction - double bond breaks, molecule splits and adds to each side of double bond Hydrogenation reaction - Double bond breaks, an H added to each side of double bond. Ni = catalyst Hydration reaction - Double bond breaks, H atom and OH atom added. H+ = catalyst Oxidation reaction - Double bond breaks, two OH groups are added to either side (needs acidic solution to produce also a changed ion (eg Mn2+). Neutral solution, compound is formed (eg MnO2)

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Rubrica: : Addition reaction of Br2 - fast reaction

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Rubrica: : Hydrogenation reaction

Rubrica: : Hydration reaction

Alkene reactions

Test for Alkenes/Alkanes

Test for unsaturation Add Br2 (aq) and shake Br2 water de-colourises rapidly, from orange to colourless, when it reacts with an alkene (eg. cyclohexene or an alkyne) The alkene is insoluble and forms a layer on top of the Br2

Test for saturation Add Br2 (aq) and shake Br2 water de-colourised slowly, from orange to colourless, with UV light when it reacts with an alkane The alkane is insoluble and forms a layer on top of the Br2

Alkynes - CnH2n-2

Unsaturated hydrocarbon - contain triple C bonds

Conditions required for reactions

With Bromine water - UV LIGHT PCl2, NH3 - No conditions required KOH (alcholic) needed for elimination of haloakanes

Substitution

An atom of group of atoms is replaced by another atom or group of atoms

Separation in layers

Non-polar/Polar separatione.g. Bromine water is polar and therefore non-polar organic reactant and product will not dissolve in water (bromohexane) - two layers form as this polar and non-polar layer, do not mix 

Cis-Trans Isomerism

Carbon - carbon double bond must be present - prevents any rotation about this bond Therefore, atoms of groups of atoms attached to the carbon are fixed in position C atoms at both ends of the double bond must have two different groups (or atoms) attached Cannot have two of the same atoms or groups of atoms attached to one of the carbons

Carboxylic acids - CnH2n+1COOH _oic acid

Reaction with sodium carbonate - acid/base reaction (-oic acid donates a proton, forming -oate ion) - sodium -oate, water and carbon dioxide are formed  Weak acids - PH>3 Higher MPts and BPts than Alcohols of similar C chain length because there are two sets of intermolecular forces per molecule. More energy is required to break those bonds compared to alcohols of same length Solubility - yes but as C chain increases, solubility decreases Acid + Metal = Metal salt + H2 Acid + Metal Carbonate = Metal salt + CO2 + H2O Acid + Base = Metal salt + Water

Amines (aminoalkanes)

Base. Weaker than NH3 NH2 group attached Turns litmus blue in water as produce OH ions  Reaction with HCl or H2SO4 - acid/base reaction (Amines accept protons from acids due to being basic) - sulfuric acid and hydrochloric acid donate protons to the amine to form organic salts MPt and BPt - as the length of the molecule increases so does the MPt and BPt of the amines. As the molar mass of the amine increases so do the intermolecular forces Solubility - Amines with a small number of carbons are very soluble. As the length of the C chain increases, amines become less soluble Can form complex ions with copper [Cu(CH3CH2NH2)4]2+

Alcohol - _ol - CnH2n+1OH

Reaction with HCl - substitution reaction - HCl replaces -OH group, forming a haloalkane Reaction with conc. H2SO4/heat - elimination reaction - OH group attached and a H atom are removed from the organic molecule. Double bond forms between two carbons creating an alkene Shape of ethanol is bent like H2O around the O atom so it is soluble in water. However, the longer the C chain, the more non-polar it is, so it is less soluble in water MPt and BPt - low because week intermolecular forces. As C chain increases, the strength of the intermolecular forces also increase so MPt and BPt increase Combustion into H2O and CO2 - clean burning, hot, blue flame Oxidation - two hydrogen's attached to the same carbon as the OH group are replaced by a double bond with Oxygen. A Carboxylic acid is formed. Needs acidic MnO4- or C2O72- Elimination - OH group is removed and a double bond is formed - poor get poorer - both major and minor products - need conc. H2SO4 Substitution - OH group replaced by a Halogen. Need PCl3/PCl5/SOCl2. conc. HCl can be used with tertiary alcohols at room temp which are small and therefore soluble in water. The Haloalkane formed is insoluble and forms a cloudy layer above the aqueous solution

Markovnikov's rule

"The rich get richer" - Hydrogen adds onto carbon attached to the most Hydrogen's "The poor get poorer" - Hydrogen atom is eliminated from the carbon with the least amount of Hydrogen's attached to it The major product (high-yeild) is one that follows rule. Minor product is the alternative

Polymerisation - poly-

An addition reaction - the formation of a long chain molecule by a larger number of alkene molecules adding together at their double bonds. If the starting alkene, the monomer is ethene, the polymer formed is polythene

Ways to test substances

Water - if soluble or insoluble  Litmus - red turned blue - basic, red stays red - acidic Bromine water - soluble/insoluble, colour change (de colourisation of orange ion)

Cycloalkanes - CnH2n - cyclo-_ane

Haloalkanes

Substitution reaction - Haloalkane is substituted in for the anion of the other reactant Elimination reaction - Haloalkane is eliminated and replaced with a double bond. Elimination is favoured when the solvent used is less polar than water. Use KOH (alcoholic). Produces major and minor products - the poor get poorer